There is an image forming system equipped with a post processing apparatus for carrying out a post-processing on a sheet and an image forming apparatus. The post-processing apparatus is equipped with various driven members. Parts of the driven members are driven by a DC (Direct Current) motor. A rotational speed of the DC motor is reduced if the DC motor approaches the end of its lifetime.
If the rotational speed of the DC motor is reduced, a drive speed of the driven member is reduced. If the drive speed of the driven member is reduced, there is a case in which a paper jam occurs or an alignment state of discharged sheets becomes faulty. In this way, if the rotational speed of the DC motor is reduced, there is a case in which a stable operation of the post-processing apparatus becomes difficult.